JP2004068874A - Universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a universal joint capable of prolonging its service lifetime by reducing a local load applied to the tip of a cross pin and thereby eliminating exfoliation due to a compressive fatigue of the tip of the cross pin. <P>SOLUTION: The universal joint is structured so that a bearing is installed between the cross pin 1 in cruciform shape and a yoke 6, wherein the gap between the periphery of the inner ring 3 and the inside surface of the outer ring 5 is made as large as the tip of a shaft 2, and the contacting area is made approximately uniform when it has received a torque, and the load applied to the tip of the shaft 2 is reduced. The arrangement introduces fit-in system in which the inner ring 3 of the bearing is fitted on the shaft 2 of the cross pin 1, and it is made possible to replace only the bearing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a universal joint suitable for transmitting a relatively large torque.
[0002]
[Prior art]
For example, in a rolling mill used in an iron mill, the power of the prime mover is transmitted to the rolling rolls via a spindle, but the rolling rolls move up and down, so that a universal is provided between the prime mover and the spindle or between the spindle and the rolling rolls. Joints are used. As shown in FIG. 11, for example, the universal joint includes a yoke connected to a drive-side shaft and a driven-side shaft, and a cross-shaped cross pin incorporated between the yokes.
[0003]
As shown in FIG. 12, between the cross pin 1 and the yoke 6, a bearing having double rows of rollers 4 is mounted. Conventionally, the shaft 2 of the cross pin 1 and the bearing are integrated, and the outer ring 5 of the bearing is fitted into the yoke 6.
[0004]
However, in such a universal joint, when a large torque is applied, the shaft 2 of the cross pin 1 is inclined with respect to the yoke 6 as shown in FIG. There was a problem that fatigue peeling easily occurred. In this case, the outer periphery of the cross pin is polished and reused. However, it cannot be reused after polishing several times, and there is a problem that the cost increases.
[0005]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and to provide a universal joint that can reduce the local load applied to the tip of a cross pin, thereby eliminating peeling due to compression fatigue at the tip of the cross pin, and extending the service life. It is a thing.
[0006]
[Means for Solving the Problems]
The universal joint of the present invention made in order to solve the above-mentioned problem is a universal joint in which a bearing is arranged between a cross-shaped cross pin and a yoke. Is characterized in that it is larger on the tip side. It is preferable that the inner ring of the bearing be of a fitting type with respect to the shaft of the cross pin. In addition, the gap between the inner circumference of the bearing roller and the outer circumference of the inner ring is increased toward the tip of the shaft, or the gap between the outer circumference of the bearing roller and the inner circumference of the outer ring is increased toward the tip of the shaft. be able to.
[0007]
In the universal joint of the present invention, the gap between the outer circumference of the inner race and the inner circumference of the outer race is increased toward the tip end of the shaft, so that even when the cross pin shaft is inclined with respect to the yoke during torque transmission, the entire inner race is substantially uniform. As a result, the local load applied to the tip of the shaft is reduced. For this reason, exfoliation due to compression fatigue at the tip of the cross pin can be eliminated, and the service life can be extended. Further, if the inner ring of the bearing is of a fitting type with respect to the shaft of the cross pin, only the inner ring needs to be replaced even when the inner ring is worn, and there is an advantage that the cross pin itself can be used continuously.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a first embodiment, in which a cylindrical inner shaft 3 of a cross-pin 1 having a tapered thinner working is shrink-fitted toward a tip thereof. The outer ring 5 of the bearing is assembled and assembled into the yoke 6. The outer diameter of the inner ring 3 is linearly tapered and is reduced toward the distal end of the shaft 2, so that a larger gap is formed toward the distal end of the shaft 2 so that the inner circumference of the roller 4 and the outer circumference of the inner ring 3 are increased. And between them. The inner ring 3 may be tapered on the inner side or the outer side. The taper is exaggerated in the drawing, but the actual taper amount is about 10 μm to 100 μm.
[0009]
When a torque is applied to this universal joint, the shaft 2 is inclined as shown in FIG. However, since the outer diameter of the inner ring 3 becomes smaller toward the tip, and the gap between the inner circumference of the roller 4 and the outer circumference of the inner ring 3 becomes larger, the outer circumference of the inner ring 3 is evenly distributed on the inner circumference of the roller 4. It will adhere. As a result, the load does not concentrate on the tip of the shaft 2 and the inner ring 3, so that the fatigue strength is increased and the fatigue separation is prevented. Moreover, if the inner ring 3 of the bearing is shrink-fitted as in this embodiment, the cross pin 1 can be semi-permanent by replacing the inner ring 3 of the bearing even if the inner ring 3 of the bearing is worn out or peeled off due to fatigue due to long-term use. This has the advantage that the service life of the bearing is extended.
[0010]
FIG. 3 shows a second embodiment, which is basically the same as the above-described embodiment, except that the outer periphery of the inner ring of the bearing is subjected to a curved taper processing. Also in this case, as shown in FIG. 4, it is possible to prevent the load when receiving the torque from being concentrated on the tip of the shaft 2 and the inner ring 3. Since the optimum taper shape and taper amount vary depending on the load condition and the size of the cross pin, it is preferable to calculate the load by a three-dimensional finite element method (FEM) analysis or the like so that the load becomes uniform.
[0011]
FIGS. 5 and 6 show a third embodiment in which the shaft 2 of the cross pin 1 is tapered so that the outer diameter decreases toward the tip, and the tapered inner ring 3 of the bearing is not tapered. Is shrink-fitted, so that the outer diameter of the inner ring 3 is reduced toward the distal end of the shaft 2. In addition to the shrink-fitting of the inner ring 3, the inner ring 3 may be formed integrally with the shaft 2 of the cross pin 1.
[0012]
7 and 8 show a fourth embodiment in which the inner diameter of the outer ring 5 of the bearing is tapered so as to increase toward the tip. As a result, a gap is formed between the outer periphery of the roller 4 and the inner periphery of the outer ring 5, the gap increasing toward the tip of the shaft 2. When a load is applied, as shown in FIG. 8, the entire roller 4 is evenly pressed against the inner periphery of the outer ring 5, so that the load does not concentrate on the ends of the shaft 2 and the inner ring 3.
[0013]
FIGS. 9 and 10 show a fifth embodiment, in which the inner periphery of the yoke 6 is tapered so as to become wider toward the distal end. In this case, the same operation and effect as those of the other embodiments can be obtained. In any of the embodiments, the inner ring 3 is shrink-fitted to the shaft 2 of the cross pin 1, and the shaft 2 of the cross pin 1 itself can be used continuously by replacing the bearing. However, as described above, the inner race 3 may be formed integrally with the shaft 2 of the cross pin 1.
[0014]
【The invention's effect】
As is clear from the above embodiment, the present invention increases the gap between the outer circumference of the inner ring and the inner circumference of the outer ring toward the tip of the shaft, so that when torque is applied, the load is applied to the tip of the shaft. There is an advantage that concentration does not occur and fatigue peeling does not occur. According to the present invention, it has been confirmed that the roller load at the tip of the bearing is reduced by about 20%, and the life of the bearing can be improved about twice. Further, if the inner ring of the bearing is fitted into the shaft of the cross pin so that the inner ring can be replaced as in the invention of claim 2, the inner ring can be replaced even when wear, peeling, etc. occur due to fatigue due to long-term use. This has the advantage that the cross pin can be used semi-permanently.
[Brief description of the drawings]
FIG. 1 is a sectional view of a main part showing a first embodiment.
FIG. 2 is a sectional view of a main part showing a state where a load is applied.
FIG. 3 is a sectional view of a main part showing a second embodiment.
FIG. 4 is a sectional view of a main part showing a state where a load is applied.
FIG. 5 is a sectional view of a main part showing a third embodiment.
FIG. 6 is a sectional view of a main part showing a state where a load is applied.
FIG. 7 is a sectional view of a main part showing a fourth embodiment.
FIG. 8 is a sectional view of a main part showing a state where a load is applied.
FIG. 9 is a cross-sectional view of a main part showing a fifth embodiment.
FIG. 10 is a sectional view of a main part showing a state where a load is applied.
FIG. 11 is an exploded perspective view of a conventional universal joint.
FIG. 12 is a sectional view of a main part of a conventional universal joint.
FIG. 13 is a cross-sectional view of relevant parts showing a state where a load is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cross pin 2 Shaft 3 Inner ring 4 Roller 5 Outer ring 6 Yoke

Claims (4)

A universal joint in which a bearing is arranged between a cross-shaped cross pin and a yoke, wherein the gap between the outer periphery of the inner ring of the bearing and the inner periphery of the outer ring is increased toward the tip of the shaft. The universal joint according to claim 1, wherein the inner ring of the bearing is of a fitting type with respect to a shaft of the cross pin. The universal joint according to claim 1, wherein a gap between an inner circumference of the bearing roller and an outer circumference of the inner ring is increased toward a tip end of the shaft. 3. The universal joint according to claim 1, wherein a gap between an outer periphery of the bearing roller and an inner periphery of the outer ring is increased toward a tip end of the shaft.

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